This invention relates to apparatus for supporting a record/playback transducer for use in a record and/or playback device and, more particularly, to such apparatus wherein the transducer and its support structure are motor driven for bi-directional sliding movement to at least first, second and intermediate positions.
Transducers, commonly referred to as heads, are widely used for recording and/or reproducing information on a record medium. For example, magnetic transducers or heads are used to record and play back information on a magnetic medium, such as a magnetic tape. To effect accurate signal recording and reproduction, the head should be disposed in good magnetic contact with the tape. Frequently, however, it is advantageous to transport the tape rapidly in a forward or rewind direction in order to access quickly a selected portion at which signals then may be recorded or played back. For such rapid tape movement, it is desirable to displace the head from the tape such that, when the tape is transported quickly, there is little contact and, thus, little abrasion of the moving tape with the head. This avoids damage both to the head and to the tape.
Various types of signal recording and/or playback devices have been introduced for use with magnetic tape housed in a cassette. Such cassette recorders are used to record and/or reproduce information in the form of analog signals or digital signals on the magnetic tape. One type of analog signal recorder records or reproduces sound (or audio) signals to function as, for example, a dictating/transcribing machine. In devices of this type, the head or heads should be movable so as to be inserted into and withdrawn from the cassette, thereby permitting audio signals to be recorded or reproduced, and also permitting the tape to be transported rapidly from one reel to the other within the cassette, and also permitting the cassette to be loaded into and withdrawn from the device.
One type of head support structure which has been proposed for such a cassette-type recorder is described in U.S. Pat. No. 4,056,835. As disclosed therein, a record/playback head is mounted on a pivotable support member which rotates through an arc so as to selectively insert or withdraw the head from the cassette. The support member and, thus, the head is driven by a selectively energizable solenoid. Another pivotable head support assembly is described in U.S. Pat. No. 3,833,922. A disadvantage of such pivotable head support assemblies is that they require a substantial amount of space in order to operate properly. Hence, recording devices which incorporate such pivotable head support assemblies often are relatively bulky and not easily miniaturizable. Such head support assembles thus are not readily incorporated into recorders which are adapted for use with cassettes of very small size.
Another type of head support assembly which has been designed for cassette-type recorders contemplates the mounting of the head on a slidable support member, for example, as shown in U.S. Pat. Nos. 3,873,993 and 4,176,383, as two typical examples. Usually, however, such slidable head support structures are mechanically coupled to push-buttons which extend outwardly from the recorder and which are operated directly by the user so as to urge the support structure and, thus, the head into and out of engagement with the cassette tape. Although such mechanically-linked slidable head support structures have been designed successfully for small-sized recorders, there is a practical limitation on miniaturization thereof. For example, the push-buttons, or levers, must be of sufficient size to be operated by the user. If the push-buttons are too small and too closely spaced, the user inadvertently might operate an erroneous push-button, thus initiating an undesired mode of operation of the recorder. Furthermore, to allow interaction, such as interlocking and release, among the various push-buttons and levers, there must be sufficient space within the recorder to accommodate the appropriate elements. Therefore, even if relatively small slidable movements are all that may be needed for proper operation of the recorder, the foregoing limitations on size reduction tend to prevent adequate exploitation of miniaturization of the recorder.
Recently, it has been proposed that the slidable head support structure may be driven for bi-directional movement by a selectively energizable drive motor rather than through direct mechanical linkages to push-buttons. Miniaturized motors which exhibit low power supply requirements can be bi-directionally energized, for example, to drive the support structure in one direction so as to engage the head with magnetic tape, and to return the support structure to its "home" position so as to disengage the head from the tape. Typically, the head is in engagement with the tape only for record and playback operations. The head is disengaged from the tape during rapid tape transport (e. g. fast forward and rewind movement of the tape), as well as during standby or quiescent (e. g. stop) modes. Unfortunately, when this type of motor-driven head support structure is used in a sound recorder such as a dictating machine, the fact that the head disengages the tape during fast forward and rewind tape movements results in difficulty for the user to transport the tape rapidly to a desired location. This is because the head, when disengaged from the tape, is spaced a relatively large distance therefrom and cannot detect signals which had been recorded on the tape. As a result, the user must initiate numerous fast-forward and rewind operations in order to advance the tape to its desired location.
Another disadvantage attending the aforementioned motor-driven head support structure is the inability therein to sense the relative location of the head with respect to the tape. Usually, the motor is energized in one direction for a period of time that is long enough to ensure that the head has been driven into proper engagement with the tape. Likewise, to withdraw the head, the motor is driven in the opposite direction for approximately the same length of time. No provision is made to move the support structure and, thus, the head to an intermediate position. Nor do such motor-driven head support structures contemplate the use of position sensing means for sensing when the head is in its engaged or disengaged positions; or of sensing when the head lies somewhere therebetween.